Advertisements
Advertisements
प्रश्न
In a meter bridge, the null point is found at a distance of l1 cm from A. If now a resistance of X is connected in parallel with S, the null point occurs at l2 cm. Obtain a formula for X in terms of l1, l2 and S.
Advertisements
उत्तर
Initially, when X is not connected
`R/S = l_1/(100 -l_1)` [Condition for balance ] ....... (1)
The equivalent resistance (Req) of the combination of X and S is
`1/R_(eq) = 1/X +1/S`
`R_(eq) = (SX)/(X+S)`
`R/R_(eq) = (l_2)/(100 - l_2)`
`(R(X+S))/(SX) = (l_2)/((100 - l_2))` ........ (2)
On dividing (i) by (ii), we obtain
`R/(R(X +S)) xx (SX)/X = (l_1(100 - l_2))/(l_2(100 - l_1)) `
`X /(X +S) = (l_1(100 - l_2))/(l_2(100-l_1)`
`Xl_2 (100 - l_1) = (X +S)l_1(100 - l_2)`
`XI_2 (100 - l_1) = Xl_1(100 - l_2) + Sl_1 (100 - l_2)`
`X = (Sl_1 (100 - l_2))/([l_2(100 -l_1) - l_1 (100 - l_1)])`
This is the expression for X in terms of S, l1 and l2.
APPEARS IN
संबंधित प्रश्न
In potentiometer experiment, if l1 is the balancing length for e.m.f. of cell of internal resistance r and l2 is the balancing length for its terminal potential difference when shunted with resistance R then :
Why are the connections between the resistors in a meter bridge made of thick copper strips?
(a) In a metre bridge [shown in the figure], the balance point is found to be at 39.5 cm from the end A, when the resistor Y is 12.5 Ω. Determine the resistance of X. Why are the connections between resistors in a Wheatstone or meter bridge made of thick copper strips?
(b) Determine the balance point of the bridge above if X and Y are interchanged.
(c) What happens if the galvanometer and cell are interchanged at the balance point of the bridge? Would the galvanometer show any current?
In a metre bridge, the balance point is found at a distance l1 with resistances R and S as shown in the figure.An unknown resistance X is now connected in parallel to the resistance S and the balance point is found at a distance l2. Obtain a formula for X in terms of l1, l2 and S.
An I0m long uniform metallic wire having a resistance of 20Ω IS used as a potentiometer wire. This wire is connected in series with another resistance of 480Ω
and a battery of emf 5V having negligible internal resistance. If an unknown emf e is balanced across 6m of the potentiometer wire, calculate
1) the potential gradient across the potentiometer wire
2) the value of the unknown emf e.
The figure shows experimental set up of a meter bridge. When the two unknown resistances X and Y are inserted, the null point D is obtained 40 cm from the end A. When a resistance of 10 Ω is connected in series with X, the null point shifts by 10 cm. Find the position of the null point when the 10 Ω resistance is instead connected in series with resistance ‘Y’. Determine the values of the resistances X and Y.
In a meter bridge, when galvanometer and cell positions are interchanged, ______.
In a sensitive meter bridge apparatus the bridge wire should possess ______.
A meter bridge is balanced with a known resistance (R) in the left hand gap and an unknown resistance (S) in the right hand gap. Balance point is found to be at a distance of 1 cm from the left hand side. When the battery and the galvanometer are interchanged, balance point will ______.
